216
May be applied to observations (p. 221)
Sec.4. The Canon of Variations 222
How related to Agreement and Difference (p. 222);
The Graphic Method (p. 227);
Critical points (p. 230);
Progressive effects (p. 231);
Gradations (p. 231)
Sec.5. The Canon of Residues 232

CHAPTER XVII

COMBINATION OF INDUCTION WITH DEDUCTION

Sec.1. Deductive character of Formal Induction 236
Sec.2. Further complication of Deduction with Induction 238
Sec.3. The Direct Deductive (or Physical) Method 240
Sec.4. Opportunities of Error in the Physical Method 243
Sec.5. The Inverse Deductive (or Historical) Method 246
Sec.6. Precautions in using the Historical Method 251
Sec.7. The Comparative Method 255
Sec.8. Historical Evidence 261

CHAPTER XVIII

HYPOTHESES

Sec.1. Hypothesis defined and distinguished from Theory 266
Sec.2. An Hypothesis must be verifiable 268
Sec.3. Proof of Hypotheses 270
(1) Must an hypothetical agent be directly observable? (p. 270);
_Vera causa_ (p. 271)
(2) An Hypothesis must be adequate to its pretensions (p. 272);
_Exceptio probat regulam_ (p. 274)
(3) Every competing Hypothesis must be excluded (p. 275);
Crucial instance (p. 277)
(4) Hypotheses must agree with the laws of Nature (p. 279)
Sec.4. Hypotheses necessary in scientific investigation 280
Sec.5. The Method of Abstractions 283
Method of Limits (p. 284);
In what sense all knowledge is hypothetical (p. 286)

CHAPTER XIX

LAWS CLASSIFIED; EXPLANATION; CO-EXISTENCE; ANALOGY

Sec.1. Axioms; Primary Laws; Secondary Laws, Derivative or Empirical;
Facts 288
Sec.2. Secondary Laws either Invariable or Approximate Generalisations 292
Sec.3. Secondary Laws trustworthy only in 'Adjacent Cases' 293
Sec.4. Secondary Laws of Succession or of Co-existence 295
Natural Kinds (p. 296);